The present invention disclosed herein relates to a method for remediating contaminated soil, and more particularly to a method for remediating contaminated soil, which has acidic property and is contaminated with heavy metals, in an exhausted mine area by using a biological and biochemical method.
Exhausted mine areas have been neglected for a long period of time without appropriate treatment of environmental contamination after mining activities such as digging, cradling, and refining. In the exhausted mine areas, severe contamination in soil and a water system of stream occurs due to release of acidic mine drainage, loss of mine tailings caused by rainfall, and spread of dust derived from mine wastes, etc.
In particular, it has been reported that arsenic, cadmium, copper, lead, and aluminum contamination levels in metalliferous mine areas are high. Moreover, in about 50% or more of the total exhausted mine area, a soil contamination level of surrounds exceeds a concern level.
To remediate the soil contaminated with heavy metals, a study has been continuously conducted to improve and neutralize acidic soil by employing, as a soil stabilizer, an alkaline material such as limestone (CaCO3), and slaked lime (Ca(OH)2), metal oxides of Fe, Al, and Mn, clay, phosphate, compost, red mud, and alum sludge.
Among the above materials, a carbonate mineral (e.g., limestone) particularly has an effect of buffering an acidic reaction according to oxidation, thereby increasing pH of contaminated soil and precipitating metal ions in an oxide- or sulfate hydroxide form. Therefore, calcium carbonate has been widely used as a neutralizer and a heavy metal stabilizer in the acidic soil contaminated with heavy metals.
Typically, remediation of soil has been conducted through the method of directly spreading limestone including calcium carbonate as a main ingredient to contaminated soil. However, spreading calcium carbonate once does not bring to a significant effect. Nonetheless, periodically spreading calcium carbonate for a long period of time is not economical.